These are characters I recently thought of making for this and other accounts. They were based on a pair of Ford Pintos my parents used to have.
Mack is a hot rodder, despite having a 2000 cc 4-cylinder engine. He likes to think he's a racing car of dragster funny car tearing up the track. He had his original bumper replaced with that of a Ford F150 pickup, because you know what happens when you rear-end a Pinto:
*EXPLOSION*
Sadie is more the "grocery getter" of the twosome. She's more the cautious type who avoids the freeways unless absolutely necessary. She gets worried whenever Mack goes around burning rubber on the street. She's afraid he'll end up wrecked by another car or impounded by the police.

Characters based on Wheelie and the Chopper Bunch by Hanna-Barbera